• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.11a
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• pp.43-44
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• 2007

• Proceedings of the Optical Society of Korea Conference
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• 2004.02a
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• pp.358-359
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• 2004

• Journal of the Korean Society for Precision Engineering
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• v.23 no.9 s.186
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• pp.102-110
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• 2006

We discuss two possibilities of using femtosecond pulse lasers as a new interferometric light source for enhanced precision surface-profile metrology. First, a train of ultra-fast laser pulses yields repeated low temporal coherence, which allows unequal-path scanning interferometry, which is not feasible with white light. Second, the high spatial coherence of femtosecond pulse lasers enables large-sized optics to be tested in nonsymmetric configurations with relatively small-sized reference surfaces. These two advantages are verified experimentally using Fizeau and Twyman-Green type scanning interferometers.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.204-207
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• 2005

We discuss two possibilities of using femtosecond pulse lasers as a new interferometric light source fer enhanced precision surface profile metrology. First, a train of ultra-fast laser pulses yields repeated low temporal coherence, which allows performing unequal-path scanning interferometry that is not feasible with white light. Second, high spatial coherence of femtosecond pulse lasers enables to test large size optics in non-symmetric configurations with relatively small size reference surfaces. These two advantages are verified experimentally using Fizeau and Twyman-Green type scanning interferometers.

• Proceedings of the KSRS Conference
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• 2008.10a
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• pp.251-254
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• 2008

The German radar satellite TerraSAR was launched in 2007. In this study, interferogram is generated using TerraSAR-X data and DEM (Digital Elevation Model). Coregistration procedures used with SAR images (i.e. master and slave) in traditional method results in serious errors for high resolution TerraSARX data because of the mutual shift of the master and slave images due to topography. This error becomes more serious in mountainous areas in which the coherence between interferometric pairs is relatively low. Here we processed a geometric coregistration with DEM exploiting height information. Through the method, interferometry processing is fulfilled to generate a qualified interferogram and coherence is improved. This approach will help high resolution X-band SAR interferometry in mountainous area.

• Journal of the Korean Society for Precision Engineering
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• v.34 no.2
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• pp.107-114
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• 2017

In this investigation, we describe a metrological technique for surface and thickness profiles of a silicon (Si) wafer by using a 6 degree of freedom (DOF) stitching method. Low coherence scanning interferometry employing near infrared light, partially transparent to a Si wafer, is adopted to simultaneously measure the surface and thickness profiles of the wafer. For the large field of view, a stitching method of the sub-aperture measurement is added to the measurement system; also, 6 DOF parameters, including the lateral positioning errors and the rotational error, are considered. In the experiment, surface profiles of a double-sided polished wafer with a 100 mm diameter were measured with the sub-aperture of an 18 mm diameter at $10\times10$ locations and the surface profiles of both sides were stitched with the sub-aperture maps. As a result, the nominal thickness of the wafer was $483.2{\mu}m$ and the calculated PV values of both surfaces were $16.57{\mu}m$ and $17.12{\mu}m$, respectively.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.10
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• pp.160-167
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• 1996

A new pathlength deviation detection technique which is composed of michelson interferometer is described and verified experimentally. The technique uses a sub-threshold biased visible laser diode of 20$\mu$m coherence length as a low-coherent light source. And for zeroth-order fringe(which is the largest among fringes) identification we used a piezoelectric transducer with a large modulation smplitude, which enables without the need of constant velocity scanning, to distinguish reflection surfaces separated by more than 10$\mu$m with a resolution of less than half-wavelength.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.288-289
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• 2003

피부 표면 굴곡의 측정은 피부의 광노화의 정량화 , 피부관련 약품 및 기능성 화장품의 효과 평가, 피부 질환 진단 등에 반드시 필요하다. 기존에 사용되던 측정법으로는 스타일러스 (Stylus)법, 그림자(Shadowing)법, Laser Profilometry법 등이 있으나 이 방법들은 해상도 및 속도, 가격 등에 있어서 일반적으로 사용되기에는 부적합하다. 본 연구에서는 이 단점들을 극복하고 더 나은 굴곡 측정을 위해서 높은 횡·종축 해상도를 얻을 수 있는 저 결맞음 간섭계 (Low Coherence Interferometry, LCI)를 이용하여 피부 표면의 굴곡을 측정하였다.(중략)

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.11a
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• pp.735-736
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• 2008

• Proceedings of the Optical Society of Korea Conference
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• 2005.02a
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• pp.48-49
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• 2005